Patterns of immune infiltration in lung adenocarcinoma revealed a prognosis-associated microRNA-mast cells network.

Immune infiltration of tumor microenvironment is an important determinant for immune response and outcomes. To investigate the diversity and clinical relevance of immune infiltration in lung adenocarcinoma (LUAD), we performed a comprehensive analysis using the bulk tumor transcriptomes. The prognosis significance for immune infiltration was systematically evaluated and sufficient immune infiltration was associated with better outcomes. Resting mast cells emerged as the most strongly associated with better overall survival (OS) and disease-free survival (DFS), whereas the activated mast cells were correlated with adverse survival. Immune infiltration-based classification exhibited clinical relevance and provided a close link between cancer cell-intrinsic genetic events and immune landscape. The immune infiltration-miRNA functional network analysis showed that the resting mast cell-associated miRNAs are mainly involved in the enrichment of development, mRNA metabolic process, myeloid cell differentiation, Wnt, calcium modulating, interferon, p53 pathways. Additionally, we found one promoter (miR-30a) and one suppressor (miR-550a) of resting mast cells. Coupling the detailed analyses of the cellular immune infiltration and the implicated modulation role of miRNAs provides novel type of candidates for LUAD immunotherapy.